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Optical qubits uniquely combine information transfer in optical fibers with a good processing capability and are therefore attractive tools for quantum technologies. A large challenge, however, is to overcome the low efficiency of two-qubit…

The three-spin-$1/2$ decoherence-free subsystem defines a logical qubit protected from collective noise and supports exchange-only universal gates. Such logical qubits are well-suited for implementation with electrically-defined quantum…

Quantum Physics · Physics 2019-04-26 James. R. van Meter , Emanuel Knill

We theoretically propose a set of universal quantum gates acting on a hybrid qubit formed by coupling a quantum dot spin qubit and Majorana fermion qubit. First, we consider a quantum dot tunnel-coupled to two topological superconductors.…

Mesoscale and Nanoscale Physics · Physics 2016-08-03 Silas Hoffman , Constantin Schrade , Jelena Klinovaja , Daniel Loss

We present a theory of quantum circuits based on logical qubits encoded in chirality of electron spin complexes in lateral gated semiconductor triple quantum dot molecules with one electron spin in each dot. Using microscopic Hamiltonian we…

Strongly Correlated Electrons · Physics 2015-05-18 Chang-Yu Hsieh , Pawel Hawrylak

Controlled operations are fundamental building blocks of quantum algorithms. Decomposing $n$-control-NOT gates ($C^n(X)$) into arbitrary single-qubit and CNOT gates, is a crucial but non-trivial task. This study introduces $C^n(X)$ circuits…

By exploiting the fermionic qubit parity measurement, we present a scheme to realize quantum non-demolition (QND) measurement of Bell-states and generate n-party GHZ state in quantum dot. Compared with the original protocol, the required…

Quantum Physics · Physics 2009-11-11 Guo-Ping Guo , Hui Zhang , Guang-Can Guo

It is shown that a quantum controlled-NOT gate simultaneously performs the logical functions of three distinct conditional local operations. Each of these local operations can be verified by measuring a corresponding truth table of four…

Quantum Physics · Physics 2009-11-10 Holger F. Hofmann

We fabricated Quantum Dot (QD) devices using a standard SOI CMOS process flow, and demonstrated that the spin of confined electrons could be controlled via a local electrical-field excitation, owing to inter-valley spin-orbit coupling. We…

Silicon quantum dot spin qubits provide a promising platform for large-scale quantum computation because of their compatibility with conventional CMOS manufacturing and the long coherence times accessible using $^{28}$Si enriched material.…

We exploit hyperfine interactions in a single Mn-ion confined in a quantum dot (QD) to create a qudit, i.e. a multi-level quantum-bit system, with well defined, addressable and robust set of spin states for the realization of universal…

Mesoscale and Nanoscale Physics · Physics 2019-09-18 Fabrizio Moro , Alistair J. Fielding , Lyudmila Turyanska , Amalia Patanè

Time-bin qubits, where information is encoded in a single photon at different times, have been widely used in optical fiber and waveguide based quantum communications. With the recent developments in distributed quantum computation, it is…

We consider a model of two interacting always-on, exchange-only qubits for which controlled phase ($CPHASE$), controlled NOT ($CNOT$), quantum Fourier transform ($QFT$) and $SWAP$ operations can be implemented only in a few electrical…

Mesoscale and Nanoscale Physics · Physics 2018-05-09 Jakub Łuczak , Bogdan R. Bułka

We successfully demonstrated experimentally the electrical-field-mediated control of the spin of electrons confined in an SOI Quantum Dot (QD) device fabricated with a standard CMOS process flow. Furthermore, we show that the Back-Gate…

Producing and maintaining entanglement reside at the heart of the optimal construction of quan- tum operations and are fundamental issues in the realization of universal quantum computation. We here introduce a setup of spin qubits that…

Quantum Physics · Physics 2017-07-12 Vahid Azimi Mousolou

Quantum computing using two-dimensional NMR has recently been described using scalar coupling evolution technique [J. Chem. Phys.,109,10603 (1998)]. In the present paper, we describe two-dimensional NMR quantum computing with the help of…

Quantum Physics · Physics 2007-05-23 T. S. Mahesh , Kavita Dorai , Arvind , Anil Kumar

The Controlled-Not (CNOT) gate is essential to algorithms in quantum computing for its ability to entangle qubits. As such, it is important to understand how students learning quantum computing reason around the function and use of this…

Physics Education · Physics 2026-04-21 Jonan-Rohi S. Plueger , Bethany R. Wilcox , Steven J. Pollock , Gina Passante

Certain quantum gates, such as the controlled-NOT gate, are symmetric in terms of the operation of the control system upon the target system and vice versa. However, no operational criteria yet exist for establishing whether or not a given…

Quantum Physics · Physics 2009-11-07 John A. Vaccaro , O. Steuernagel , S. F. Huelga

Based on our recent paper [arXiv:2206.12176 (2022)], we propose a scalable heteronuclear architecture of parallel implementation of CNOT gates in arrays of alkali-metal neutral atoms for quantum information processing. We considered a…

Quantum Physics · Physics 2023-10-02 Ahmed M. Farouk , I. I. Beterov , Peng Xu , I. I. Ryabtsev

In this review we discuss a recent proposal to perform partial Bell-state (parity) measurements on two-electron spin states for electrons confined to quantum dots. The realization of this proposal would allow for a physical implementation…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 W. A. Coish , Vitaly N. Golovach , J. Carlos Egues , Daniel Loss

We give a general method of construting quantum circuit for random \QTR{it}{satisfiability} (SAT) problems with the basic logic gates such as multi-qubit controlled-NOT and NOT gates. The sizes of these circuits are almost the same as the…

Quantum Physics · Physics 2007-05-23 Xinhua Peng , Xiwen Zhu , Kelin Gao